HomeMy WebLinkAboutAPA1286'1.
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
TASK 6 -DESIGN DEVELOPMENT
SUBTASKS 6.09 & 6,10 -DESIGN CRITERIA
FOR WATANA AND DEVIL CANYON DEVELOPMENTS
NAY 1981
ACRE_S AMERICAN INCORPORATED
1000 Liberty Bank Building
Main at Court
Buffalo, New York 14202
Telephone-(716) 8.53-7525
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TABLE OF CONTENTS
Page
1.0 -GENERAL • • ~ • • • • • • • • • • • • • • ~ • • ~ • • • • • • • • • • • • • • • • • • • • • • • • • • • 8· •
2 .. 0-PROJECT PARAMETERS •••• ~ •••••••••••• ., ..................... .
3. 0 -~ PROJECT DESIGN DATA ........... • • ••••••••••••••••••••••••• ~
3 .. 1 -Topographi ca 1 Data •••..•• -.............................. .
3.2 -'Hydro 1 ogi ca 1 Data .................................... -
3.3-Meteorlogical Data ................................. .
4.0 .. DESIGN CRITERIA ... 8 •••••••.•••••••••••••••••••••••••• e •••••
_ 4.1-Civil Design·····················~················· 4 .• 2-Hydraulic Des·ign ••••• ; ............................... .
4~3-Geotechnical Design ····~··························· 4. 4 -~1ech arii ca 1 Desi gn ••••• -................................ .
4.5-Electrical Design ···········~······················
5.0 -ENVIRONMENTAL RESTRICTIONS ••••••••••••. ., •••••••••• ,. •••••••
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1.0 -Genera 1
Susitna Hydroelectric Project
Project Parameters and Design Criteria
The following sets out the princi pa 1 project parameters and the design criteria
for the proposed Watana and Devil Canyon hydroelectric projects.
Much of this document is tentative at this stage as it will be subject to
confirmation or revision throughout the feasibility study. It is intended that
with further amendment as additional data becomes available it will form the
basis for the final engineering design criteria and it is broken down into
genera-l project parameters and design criteria for the individual engineering
disciplines in such a fashion as to be readily incorporated into this final
criteria. -
2.0 -Project Parameters
----
Item-
River Flows
Average flow (over 30 yrs of
record)
P~obable Maximum flood
Max. flood with return
period of 1:10,000 yrs
Max. flood with return
period of 1:500 yrs.
Max. flood with return
period of 1:50 yrs.
Normal maxo operating level
Minimum operating level
Area of reservoir at max.
operating 1 eve 1
Watana
7,860 c.f.s.
235,000 c. f. s.
155,000 c.f.s.
116~000 c.f.s.
87~000 c.f.s.
2,200' MSL
2,050' MSL
40~000 acres
8,960 c.f.s~
270,000 c. f. s.
135,000 c .. f.s
(after routing
through Watana)
42,000 c.f .. s.
(after routing
through Watana)
1,445' MSL
1,440' MSL
21,000 acres
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Item
Reservoir live storage
Reservoir full storage
Dam
Type
Crest elevation
Crest length
Height
Cut-off and foundation treatment
Upstream slope
Downstream slope
Crest width
Diversion
Cofferdam types
Cut-off and foundation
Upstream cofferdam crest elevation
Downstream cofferdam crest
elevation
Max. pool level during constructio
Min. pool level during constructio
Watet" passages
Watana
4.6 X 106
acre ft
10.0 X 106
~ere ft
Rockfi 11
2,225' MSL .
890 ft above ·
foundation
Core founded on
Grout curtain &
downstream drains.
1V:2.75H
1V:2.0H
80 ft
Rockfi 11
1560' MSL
1500 1 MSL
1555' MSL
.Dev1
'II
0.75 X 106
acre ft
1.1 X 106
acre ft
Concrete arch
1455' MSL
670ft above
foundation
on
Founded on rock.
Grout curtain &
downstream drains.
20 ft
Rockfi11
Founded on alluvium
with slurry trench
to rock. ·
960' MSL
900' t4SL
955 1 MSL
Approx. 10 ft above Approx .. 10 ·ft above
crown of outlet crown of outlet
Concrete lined Concrete lined
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Outlet structures
Final closure
Releases during impounding
Eme~gency Releases
Draw down requirements
Discharges
Water passages
Outlet structures
Gate chambers
Energy dissipation
Spillway
Design Floods
Watana
Low level struc-
ture with high head
slide gates to op-
erate under low ·
heads.
Mass concrete plugs
in line with dam
grout curtain.
2000 c.f.s. min.
vi a bypass to out-
let structure
To be determined.
To be determined.
' Concrete l7ned tun-
nels discharging
into downstream.
diversion tunnels.
Mid reservoir level
Underground cham-
bers housing wheel
mounted control
gates.
To be determined.
Passes p.m.f.~ pre-
serving integrity
of dam with no loss
of life.
Passes routed
1:10,000 yr. flood
with no damage to
structures.
955' MSL
Mass concrete plugs
in line with dam
grout curtain.
2000 c.f.s. via low
level Howel~ Bunger
valves.
Passes p.m.f.!l pre-
servi ng i ntegri ty
of dam with no loss
of life.
Passes routed
1:10,000 yr. flod
. with no damage to
structures ..
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Item
Main spillway-Capacity
-Control structure
-Energy Di ssjpation
Secondary-spillway -Capacity
-Control Structure
-Energy Dissipation
Emergency spi llway -Capacity
-Type
Power Intake
Type
Number of intakes
Draw-off requi rements
Gate chambers
Drawdown
Penstocks
Type
Number of penstocks
Powerhouse
Type
Tr an sf ormer area
Control room & administration
Access -Vehicle
-Personnel
Watana
Routed 1:10,000 yr
flood (llS,noo cfs)
with Sl surcharge
Gated ogee crests~
· To .be determined.
Not applicable.
P.m.f. minus l:lp,ooo yr flood
•
Fuse plug
Massive concrete
structure embedded
in rock.
4
Multi -1 eve 1 corres-
ponding to tempera-
ture strata.
4
Underground
Separate gallery
Surface
Rock tunne 1.
Elevator from
surface.
Devi
45,000 c.f.s.
P.m. f. minus r'outed
1:10,000 yr f1t.10d
(135,000 cfs)
Fuse plug.
Massive concrete
structure embedded
in rock.
4
Multi-level corres-
pondi ng to tempera-
ture strata.
Not determined.
Concrete lined rock
tunne 1 s with down-
stream steel liner.
4
Underground
Not determined.
Not determined.
R{!ck tunnel.
Not determined.
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Power Plant
Type of turbines
Numb~r and rating
Rated' net head
-· Des-i gn Fl ow
Maximum gross head
Maximum flow
Type of generator
Rated output
Power factor
Frequency
Transformers
Tailrace
Water passages
Elevation of water passages
Surge
Number of penstocks
Tailwater elevations
-Full generation load at
minimum head
-Single generating unit, 60%;
1 oad, fu 11 head
-Spillway passing 1:10,000 yr
· flood
Watana
Francis
4 x 270 MW
680 ft
5,300 cfs per unit
745ft
Vertical .
synchronous
310 MVA
0.9
60HZ
310 MVA
13.8-345 kv~_ 3-pnase
2 concrete lined
tunnels.
Below min. tail-
water
Separate surge
chambers.
)
1460 I }
)
)
1455' )
)
1475 1
Francis
4 X 150 MW
550 ft
3630 cfs
Canyon
565 ft approx.
Vertical
s,nchronous
172 f,1VA
0.9
60 HZ
To be determined
13.8-345 kv, 3-p_hase
2 concrete lined
tunnels.
.Below min. tailwater
Draft tube gate
shafts act as surge
shafts.
Both assumed at 880 •
MSL at this stage.
9lor MSL assumed
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3.0 -PROJECT DESIGN DATA
3.1 -Topographical Data
The topography of the site is based on aerial survey mapping reduced to a scale
of 1 inch:200 feet. Contours a·re at 5 feet intervals •
3.2 -Hydrological Data
The hydrolog.ical data is based on records taken over .a period of 30 years.
Streamflows and respective drainage areas are extrap-olated and adjusted to give
a repre.sentative pattern of flows at the damsite. Flows are shown on Tcrb1es
and . • . . --
3.3 -Meteorlogical Data
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4.0 -DESIGN CRITERIA
4.1 ~ Civil Desi9n
·4.1.1 -Governing C .. odes and Standards
Where specific standards and design criteria are not covered in this
criteria than the following codes and standards shall apply:
-American Concrete Institute 11 Building Code Requirements for Reinforced
Concrete" (ACS 318-77}.
4.1.2 -Design Loads
(1) Dead Loads:
r~ass concrete
Reinforced concrete
Steel
Water
Silt-vertical
-hori zonta 1
.Backfi 11 (a 11 dams)
-dry
-sat\Jrated
~ submerged
(2) Backfi 11 toads
145 lbs/ft3 (143 1bs/ft3 when
150 lbs/ft3'
490 lbs/ft3
62.5 lbs/ft3
120 · 1 bs/ft3
85 1bslft3
115 lbs/ft3)
130 lbs/ft3)
70 lbs/ft3)
checkin~ stability)
-Provisional
The lateral earth pressure against vertical faces of structures with
horizontal backfill will be computed using the equivalent fluid
pressures calculated from:
p =Kwh
where p = unit pressure, k = pressure coefficient, w = unit weight of
fill, h = height of fill. ·
For structures free to deflect the pressure coefficient will be
computed from -Rankine•s theory, which is:
·--kA = ton2 ( 45•0/2)
where 0 = angle of internal fricti.on •
For structures restrained-from using the pressure coefficient will be·
K0 = 1 -~in 0. ·
0
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Coulomb•·s theory wi 11 be used for computing lateral earth pressures on
oWall surfaces With slopes flatter than 10 vertical: 1 hor_izontal or
with sloping backfill ste-eper than·l vertical: 4 horizontal ..
:where verhi cul ar traffic can run adjacent to the face a surcharge
loading of 500 lbs/ft3 sho.uld be applied.
(3) Wind Loads
(4) Snow Loads
{5)
(6)
(7)
Powerhouse Floor Loads
Generator Hall
Machine Shop
Switchgear Room
Service Bay
Control Room
Transformer _Ga1lery
Offices and Sta,rs
Crane Loads
.. 500 lbs/ft2
.... 500 lbs/ft2
-300 lbs/ft2
1000 lbs/ft2
-200 lbs/ft2
300 1bs/ft2
-100 lbs/ft2
The following percentages shall apply to the powerhouse crane and the
power intake gallery. The minimum deflection t·o span ratio of crane
support beams sha 11 be l: 1000.
Vertical impact -25% of static wheel load
Lateral load -10% of crane capacity, trolley, hook$ ·and lifting_
beam distributed equally between rails .•
Longitudinal load -10% of static wheel loads.
Spillway Deck loads
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{8) Hydraulic Loads
All structures shall be designed for full lateral water pressures,
where applicable, plus ~ull hydrodynamic and uplift forces.
. Uplift
(a) For water retaining concrete structures provided with drainage
galleries and drail holes deep into the foundatiqns, uplift shall
be considered across the complete rock/concrete interface varying
,linearly from Hr to the upstream heel to (Hl-H2}/2 + H2
at the drains to H2 at the toe~
~'..~~c. ~ ~\:~'r
c~~~ \,_\c&,~~
H1 = static head upstream
H2 -·static head downstream
If uplift exceeds the beari-ng pressure (resulting from all forces
except uplift) at the heel the uplift is to be redistributed
inaccordance with USBR No. 19~
{b) Apron and chute slabs and slab walls against rock shall be
designed against uplift resulting from sudden changes in water
level.
Uplift from centrifugal forces shall be considered where
contra.cti on joints occur on concave floor of chutes~
Toe curve pressures on interior face of training walls at, concave
chute surfaces shall be calculated in accordance with Plate 21 of
Hydraulic Design of Spil1ways EM 1110-2-1603 by U .. S. Army Corps
of Engineers.
Hydraulic loads due to earthquakes are given in the following
·section on seismic 1 oads.
(9) Seismic Loads ·
Gr.ound acceleration corresponding to maximum credible earthquake-
0.4 g •
Design earthquake return period -100 yrs.
Ground acceleration corresponding, to design earthquake-0~2 g.
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Arch. Dam at Devi 1 Canyon
The arch dam is to be checked under seismic 1 oading by dynamic
analysis based on trial load method and the A.DSAS program developed by
the Department of the Inter·i or.
Arch dam system damping ratio -0.10 of critical •
Acceleration_response spectrum -See Figure 1. at Devil Canyon
Concrete Gravity Structures_
For concrete gravity structures the horizontal force (V) due to
earthquake ratio sha 11 be:
V = 0.1 x ground acceleration x mass of structure •
. Hydrodynamic .. Pressure
The hydrodynamic pressure due to hori zonta 1 earthquake on water
retaining surfaces shall be computed using the theory of Westergard
for the dynamic change in pressure:
P = a. 51.25 hy lbs/ft2
where h = total height of structure {ft)
y = depth below reservoir surface
a :: ground acceleration ·
The d1 stri buti on of pressure is par abo 1 i c and hence the tot a 1 force
and movement at a section y ft below water level are given by:
F = 2/3. P .y
M = 0.4. F.y
For hydrodynamic .forces on earth structures see Section • ---
(1'0) Temperature
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(11) Ice Loads
4.,1.3-Load Combinations
4.1.4-Stability
Shear Friction F acto·r
The shear friction factor is given by shear friction factor =
CA + (V-'U) tan 0
C ·= cohesion
A = base area
H --
V = total weight of structure
U = total vertical uplift force
0 -= angle of internal friction
4.1.5 -Stability Requirements
Concrete. Gravity Structures
Shear Friction
Load Conditio~s Factor
Flotation Compression
Normal
Unusual
(Including
1:100 yr
earthquake
Extreme
Overturning Factor Safety Fac:_~
4 based on
concrete
5 based on
rock
II
Resultant
within the
Kern
Resultant
within the
Kern
3.5 based on Maxn allow-
concrete, 4.5 ·able tension =
based on rock 30 psi
1.5
1.3
1.3
3 based on
concrete
4 based on rock
2.5 based on
concrete, 3.5
based on rock
2 .. 5 based on
concrete, 3.5
based on rock ' '
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Arch Dam
Compression Safety Factor, normal loads - 4
extreme - 1
Tension, normal loads
extreme
4 .1. 6 -Materi a 1 . Proper~_; es
4.2 -Hydraulic Design
4.2.1 -Reservoir Levels
-no tension
.... full tensile strength of
·concrete
Reservoir 1 eve ls are tentati ye at this stage and wi 11 -change with
opti mi zati on of the maxi mum pool 1-eve 1, and with the determination of the
live storage .
.
Operating Level s
Normal maximum
Normal minimum
Flood Levels·
1:10.,00 yr
p.m.f • .,
4.2.2 -Freeboard
Watana
2200' MSL
2050' MSL
2205' MSL
222s• MSL max.
Devil CanYQn
1445' MSL
1450 1 MSL
1455 1 MSL
Allowance for wave height and run up.:.. 6 feet
Allowance for flood discha~ge above
normal maximum operating 1 eve 1 -5 feet
Area and Storage
Are.a at norma 1 maximum operating
level ·
.
Live storage
'Full storage
Watana
40,000 acres
-4-~6,.-X-c...l02--acr·e/ft
10 x 106 ·acre/ft
. Devi 1 Canyon
21,000 acres
n. 7 x 106 acre/ft
1 .. 1 X 106 ac:re/ft
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· 4.2 •. 3 -Tai lwater
Water Levels
1:10,00 yr flood
1 unit operating
Average tai lwater 1 eve 1
4 . 2 • 4 ... _-Flows
Watana ·
1475' MSL
1455• MSL }
1460 1 MSL )
(See Figure 4,, flood volume/frequency curves)
Mean annual inflow
1:50 yr flood peak-inflow
1:500 yr flood peak inflow
1:1000 yr flood peak inflow
Probable maximum flood
Routed 1:10,00 flood peak
Minimum downstream releases
'Watana
7 ,86_0 cfs
116,000 cfs
155,000 cfs ~
235,000 cfs
115,000 cfs
* After routing through Watana
4.2.5 -Criteria
4.2.5.1 -Spillways
Capacity
Devil Canyon
910' MSL
880' MSL
(assumed)
Devil Canyon
8,960 cfs
135,000 cfs*
270,000 cfs*
135,000 cfs
-Pass p.m.f. while maintaining the integrity of the main water
retaining structures. local damage to these structures is
a 11 ow ab 1 e. , ·
... Pass routed 1:10,000 yr flood with no damage. A main service
spillway for general operation with a secondary spillway operated
only for shott duration is acceptable.
Chute
-Maximum velocity 150 fps without aeration.
Energy Dissipation
-Minimum radius of flip bucket> 7 x depth of design flow ..
-Max energy dissipated by stilling basin -45!t000 hp/ft width.
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4.2.5.2-.Power_Facilities
4.3 ~ Geotechnical Criteria
4.3.1 -Main Dam
(1) Dimensions
Crest elevation
Maximum height above lowest foundatin
Crest width
Upstream slope,
Downstream slope
(2) Design Criteria
-2245' MSL -goo• approx.
80'
-1:2 • .75*
-1:2*
The dam wi 11 be checked for norma 1 static 1 oadi ng conditions such tts
end of construction~ normal operating cofferdam and drawdown
condition. -
The dam wi 11 be designed to. withstand the maximum credible
earthquake.
4.3.2 -Excavation
Rock cuts at structures -slope lOV:lH (overall}
Permanent rock cuts -slope4V:lH (overall}
Permanent cuts in overburden-slope 1V:2H (overall)
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4 .A ... Mechanical Criteria
4. 4 ~1 -Power Intake
(1) Trashracks
Type
Maximum gross velocity
through racks
Handling
Number
(2) Gates
Type
Handling ·
Number
( 3) Bu-1 khead Gate
Type
Handling
Number
4.4.2 ~ Powerhouse
(1) Turbines
Type
Number
Head -maximum
-rated
-minimum
Rated discharge
Rated output (full gate)
Best gate output
Efficiencies -full gate
-best gate
Watana
flat
4 f.p.s.
·Gantry crar.e
4 sets
Watana
Fixed wheel
vertical
Indivi udal
holst
4
W·atana
Bulkhead
Gantry crane
one set
Watana
Vertical francis
4
715 ft*
680 ft*
565 ft*
5300 cfs.
370,000 hp**
85% ful1 gate
90%
93.5%
" }.
Devi 1 Canyon
flat
4 f.p.s.
Gantry crane
4 sets
Devi 1 Canyon
Fixed wheel
vertical
Individual hoist
4
D.evil C~nygn
Bulkhead
Gantry crane
one set
. Devil Canyon
Vertical francis
4
554 ft*
550ft*.
550 ft*
3630 cfs
205,000 hp
85% full gate
90%
93.5%
* To be revi-sed after determination of reservpir level and live
stor~ge ..
.
**Likely to change to smaller units!
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{2) Powerhouse Crane .
Type -overhead traveling
Number - 2
Capacity -sufficient to lift generator rotor and follower.
(3) Draft -Tube Gates
Bulkhead gates handled by fixed overhead hoist.
(4) Tailrace Outlet
. . ..
Stoplogs handled by mobile crane.
4.4.3-Spillway
(1) Gates
-Number . . . • . • • • • . . • . . . . .. • • • • . . • • . . • • • • to suit design f load
-Size ••••• ~ • • . •. • • • • • • • • • • • • • . • . • . • • • • • maxi mum size = 45 ft wide
- T .w.e •. . . . • . . S' a • 9 • • "' • • .. • • • • • 0 • • • • • .• .• • • •
-Hoisting ' ...•.•......•................•..
(2) Stoplogs
X 65 ft high
fixed _wheel vertical lift~
heated or winter operation
wire rope hoist on tower and
bridge structure
One set handled by mobile crane and fa llower.
4.4.4 -Outlet Works and Low Level Outlets (Watana only)
..
(1) Gates
-Either fixed wheel vertical lift, radial or sli-de gates; operated by
hydraulic hoist.
-Gate. head and width to be within current precedent. ·
-Emergency gate to be p.rovi ded upstream of control gate.
(2) Valves
-Fixed cone full discharge valve.s with ring follower gate upstream
for emergency closure.
(3) Stoplogs
-One s.et stop 1 og guides at upstream entrance of tunnel.
{4) Trashracks
-Located at 'upstream entrance of tunne 1.
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4.4.5 -.Diversion
(1) Closure Gate
-Fi.xed wheel vertical lift gates handled by gantry crane or fixed
wheel tt
(2) Control Gate
-As per gates by lo.w level outlet and outlet works.
(3) Stoplogs
-Where required, handled by mobile crane.
4.5 -Electrical Criteria
4.5.1 -Generators
Number
Type
Rating
Power factor
Efficiency
Transformers
Number
Rating
Voltage
Phases
Switchyard
~I at ana
4
Verti ca 1 ·synchronous
310 MVA**
0.9
98%
Watana
4
300 MVA**
13.8 kV -345 KV
3
Type -Conventional outdoor swi tchy~llrd.
*~lr Likely to change to smaller units.
~ '-··j . '" ' ....
Devi 1 Canyon
4
Vertical synchronous
165 MVA.
0.9
98%
Devi 1 Canyon
4
\6G ..JatrMVA
13.8 kV -345 kV
3
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RESERVOIR AREA ( JOOO ACRES)
40 3S 30 _zs 20 IS 0
2200 .
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""" -
~ 1800 ~----~~~----------~~--~----~---------~~--------~
tf ORIGINAL AREA--a: ::>
(I)
1600° ~--------~----------~----------~~----------~------~~
t500 ~--------~----~----~----------~----------~--------~
1400
0
STORAGE CAPACITY (MIU.JON AC. F1:)
AREA AND CAPACITY CURVES
.WATANA RESERVOIR
8
FIGURE'
10
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1809
t700
1600
-,..:
11...
-1500
z
0 -...
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"" 1400.
(300
1200
llOO
1000
25
0
RESERVOIR AREA {1000 ACRES)
20 15 10 5
ORiGINAL. AREA
""-.-.INITIAL CAPACtTY
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2
STORAGE CAPACITY (MILLION AC FT.}
A"REA AND CAPACITY CURVES
...._.D. C. RESERVOIR
Fl GURE: ftl .
0
.
5